it seemed that Douglass used a high level of benevolent vocabulary when he described Mrs Auld and depravity when he described some qualities that were not innate to her. This alteration could have made this massage more convincing or credible to those people in a powerful position. What is more, through his writing he showed that slaves did not lack of intelligence.
In this situation, Huck is trying to be impressive. He is trying to get the point across that he is funny and "cool". This lie is not only the one of a kind for Huck, but also one where he tries to push his reputation past its limits.